Tank base

ABSTRACT

A method for the construction of an improved tank base. A tank base is constructed for protection against accidental spills and/or leaks associated with a tank battery. The improved tank base comprises at least one part of a suitable substrate, which allows for the adhesion of an elastomer such as polyurea. Polyurea is preferably applied using a spray device which yields an average coverage of about 50-80 mils, and most preferably 60 mils. If more than one substrate is used, one or more substrates can be bound together with a fastening system. Once pressure is applied in the form of weight, the fastening system can be removed, resulting in an improved tank base having at least one seam and impervious to the fluid of the tank battery.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalPatent Application No. 61/106,778 filed Oct. 20, 2008, the technicaldisclosures of which is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a structural element that provides loadbearing support and the method for the production of same. Inparticular, an encapsulated polystyrene structure serves as a loadbearing material for use in protecting against accidental spills andleaks associated with any type of storage, tank, or vessel.

2. Description of Related Art

During the production of oil and gas from an underground well, it iscommon for water to be produced along with the oil or gas. This water,called “produced water,” is typically separated from the oil or gas atthe well site and temporarily stored in an above-ground storage tank, orAST (or combination of ASTs). The produced water varies in quality fromone well to the next, and it can have high quantities of minerals,salts, oil, gas, sand and other substances dissolved, mixed or suspendedin it. Produced water with a high concentration of impurities can becorrosive to the walls and ancillary piping of an AST and it can betoxic to the environment. A vehicle with a large storage tank attachedto it periodically travels to the well site and transfers the producedwater from the AST to the storage tank or vessel on the vehicle.

FIG. 1 illustrates an AST 100 with an input stream 18 and an outletstream 20. The flow rate of the outlet stream 20 is manipulated by wayof a valve 22. The produced water travels from the undergroundhydrocarbon bearing formation 6, up the oil or gas well bore hole 4,into what is known as a “Christmas tree” 10, which is an assembly ofvalves, pipes and fittings used to control the flow or oil and gas froma well. The water separating section 14 of the Christmas tree 10 directsthe produced water to the AST 100. Other separating sections 12 directthe oil or gas into a pipeline 16, which transports the oil or gas toother locations for further processing or sale. A manway entrance 350enables a technician to view the interior of the storage tank andinspect the tank for leaks, while the plumbing connections 380 to thestorage cavity of said tank enable pumping of the contents therein. Asseen in the side view in FIG. 1, the manway 350 extends below the bottomof the tank.

Accidental spills or leaks can occur for a variety of reasons. Forexample, FIG. 2 illustrates the AST 100 of FIG. 1 after the producedwater has corroded the walls of the tank, creating a hole 26 in the wallof the AST. The hole 26 allows the produced water to spill or leak outof the AST 100 and onto the ground 2. In order to protect theenvironment from an accidental discharge such as the one illustrated inFIG. 2, approved ASTs are typically required to retain any and all fluidsuch that contaminate are prevented from entering the environmentsurrounding the well site. Fluid accumulates within ASTs and secondarycontainment systems from multiple sources including natural andaccidental leaks or spills. ASTs usually need to have the capacity andstrength to hold at least 150% of the volume of the AST, or for an arrayof ASTs, 150% of the largest AST in the array.

Currently, protection for the tank, soil and equipment in thecontainment of the top soil involves the use of a grade band of metalfilled with pea gravel below the containment tank. The grade band metalis typically bolted together to form a base greater than the diameter ofthe containment tank it supports. The diameter of the support structure(base and pea gravel) is typically 3″ to 6″ greater than that of the ASTbeing supported and allows for the AST to sit approximately 3″ to 6″ inheight off of the floor of a secondary containment area. This allows theAST or containment tank to be at a level greater than the ground leveland aids in the slow deterioration of the tank due to any standing fluidwithin the secondary tank area, whether the fluid is natural (such asrainwater) or accidental (spills or leaks). The pea gravel currentlyused is naturally porous and allows for the absorption for any number ofcontaminants (i.e., oil, salts, acids, etc.) that come into contact withthe gravel, causing permanent contamination, which still tends to spillout of the gravel upon oversaturation. Attempts to treat or wash out thecontaminants are costly, difficult, and to-date, ineffective.

Consequently, a need exists for a more efficient, effective, andconvenient method for building an improved tank base to provide forsafer environment and green waste. There is a need for an improved tankbase, capable of being steam cleaned of any contaminants to provide moreenvironmentally friendly standards while maintaining other advantages ofa tank base and reducing costs associated with maintenance orreplacement of failing tanks. There is also a need for a tank base thatprovides for a more efficient and cost-effective means of the shipping,transporting, and installation into customer sites. Further, there is aneed for a method which keeps out moisture, preventing the proliferationof bacteria which often causes erosion of tanks from the inside out.

SUMMARY OF THE INVENTION

The present invention provides a method for the encapsulation of a corematerial, which allows for the adhesion of an elastomer such aspolyurea. In one embodiment, at least one part of a substrate such asexpanded polystyrene (EPS) is designed or shaped and subsequently coatedwith polyurea for protection and strength. Preferably, the foam materialcomprises a density of at least two pounds per cubic foot of foam weightwith an average coverage of about 50-80 mils and most preferably about60 mils polyurea. Other suitable substrates (including withoutlimitation wood, metal, concrete, paper fiber, fiberglass, fiber board,and gravel) allow for the adhesion of polyurea, which is preferablyapplied using a spray device. This allows for the protection of anabove-ground storage tank (AST) system in addition to a moreconveniently portable installation.

In a second embodiment, more than one part of a substrate is shaped asdesired or needed to fit beneath a tank. Each substrate is individuallycoated with the polyurea and the coated materials are then fastenedtogether around the outside circumferential periphery of the base andheld together under the weight of an AST. The materials comprise atleast one seam to allow for moisture to pass through such that nocorrosion of the tank is experienced as a result of any standing fluidfrom accidental spillage or natural rainwater. Once pressure is appliedin the form of weight, the fastener can be removed, resulting in animproved tank base having at least one seam and impervious to the fluidof the tank battery or within a secondary containment system. Thepolyurea-covered EPS is biodegradable and allows for steam cleaning tobe rid of contaminating hydrocarbons and green waste disposal, ifnecessary.

Other aspects, embodiments and features of the invention will becomeapparent from the following detailed description of the invention whenconsidered in conjunction with the accompanying drawings. Theaccompanying figures are schematic and are not intended to be drawn toscale. In the figures, each identical or substantially similar componentthat is illustrated in various figures is represented by a singlenumeral or notation. For purposes of clarity, not every component islabeled in every figure. Nor is every component of each embodiment ofthe invention shown where illustration is not necessary to allow thoseof ordinary skill in the art to understand the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself, however, as well asa preferred mode of use, further objectives and advantages thereof, willbe best understood by reference to the following detailed description ofillustrative embodiments when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is an illustration of a prior art above ground storage tank at awell site.

FIG. 2 is an illustration of a prior art above ground storage tank witha hole in its wall.

FIG. 3 is an illustration of above ground storage tank situated over atank base of the present invention.

FIG. 4 is an illustration of top perspective view of one embodiment ofthe tank base of the present invention.

FIG. 5 is an illustration of a side perspective view of the embodimentof the tank base of the present invention seen in FIG. 4.

FIG. 6 is an illustration of a side perspective view of an alternateembodiment of the tank base of the present invention.

FIG. 7 depicts a top perspective view of an alternate embodiment of thetank base of the present invention.

FIG. 8 depicts the side view of the alternate embodiment of the tankbase of the present invention illustrated in FIG. 7.

FIG. 9 depicts an alternate embodiment of the tank base of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention involves an improved method for the constructionof a tank base for use in a secondary containment area, storagefacilities or any type of vessel. While the tank base of the presentinvention is described in terms of a secondary containment for a varyingsizes of an AST, one skilled in the art, armed with this disclosure,will recognize that the present method and its resulting tank base isapplicable to any number of secondary containment systems and vesselstorage areas. Thus, while FIG. 1 depicts a cylindrical AST with itsaxis oriented perpendicular to the ground 2, one skilled in the art,armed with this disclosure, will recognize that the claimed inventionworks equally well within secondary containment systems of varyingorientation, shape and positions relative to the ground or environmentbeing protected. Further, as will be described below, the tank base ofthe present invention can be modified or custom built to accommodate anysize and shape desired.

The exterior bottom portion of an AST is particularly susceptible todamage resulting from standing fluid when the AST is sitting directly onthe floor of a secondary containment area. As described above, currentmethods of resolving this problem involves the use of a large tank basehaving portions bolted together and filled with pea gravel, whichpermanently absorbs contaminants. Current methods are labor intensiveand require multiple parties to construct and supply the tank base.

FIG. 3 illustrates an AST 100 situated over the center portion of a tankbase 300 of the present invention. As described above, moisture fromstanding water around the edges of a tank pose a problem for themaintenance of a tank 100 and contamination of the soil beneath thetank. The manway entrance 350 is illustrated in FIG. 3, depicting thatportion of the tank to which access is granted for maintaining the tank,and is shown to extend now to the top of the tank base of the presentinvention. Thus, the containment base allows the tank 100 and plumbing380 to be situated higher up from the ground, providing easier accessthrough the manway 350. Preferably, any flat portion on the tank base isaligned with the manway entrance 350 to allow for ease of entry. In theembodiment seen in FIGS. 3 and 4, the tank base comprises three parts320, 340 and 360 and two seams 310 in between each piece; however, asfew seams as possible are preferable and if desired, one solid base withno seams is also possible. For ease of transfer and construction, thebase is typically comprised of at least two parts or substratespositioned adjacent and secured to one another, creating an outerperiphery around which a fastening system is employed to bind thesubstrates together.

As used herein, the term “suitable substrate” is used synonymously with“substrate” and is meant to include without limitation, concrete, metal,EPS, wood, concrete, paper fiber, fiberglass, fiber board, and gravel orany other substrate appropriate for the adhesion of a polyurea elastomercoating. Polyurea is an elastomer derived from the reaction between anisocyanate component and a resin blend component. Polyurea suitable forthe present invention is available from Sherwin Williams under the nameENVIROPLASTIC® AR200HD or Versaflex under the name FSS 50DM. Currently,landfills and dike systems utilize secondary containments comprising EPSencapsulated with earth. Without being bounded by theory, it is believedthat the present invention provides an improved tank base in part due tothe high compressive strength of EPS in combination with the highadhesion rate and strength of polyurea, which helps encapsulate thepolystyrene and keeps it from flaking off and failing under the weightof a the tank. While Applicants describe the present invention in termsof EPS due to its environmentally friendly nature and powerful designelements, other substrates having a compressive strength are alsopossible. EPS is 100% recyclable and in some parts of the world iscurrently already being recycled at higher levels than either glass oraluminum. Used polystyrene is biodegradable and has no impact on theenvironment even in landfill sites or in incinerators, nor does itcontain substances that could pollute the air or soil. Further, themanufacture of EPS solutions does not release hydrosoluable substancesthat could contaminate ground water supplies. Suitable EPS materials arecommercially available.

The method by which the present invention is constructed will now beexplained. The first step is to design the substrates to be encapsulatedas support for a tank battery or in a secondary containment system. Asused herein, the designing step is meant to include the cutting, shapingor forming of the substrates into custom shapes or sizes to be used withvarying sizes of tanks or within a given containment area. At least onesubstrate is designed to customer requirements and according to the sizeand diameter required for the tank battery. As depicted best in FIG. 4,the measurements x and y can vary to any number depending on thesecondary containment system or AST to be supported. In test runs, atank weighing approximately 110 thousand pounds called for EPS having afoam density of 2 pounds per cubic foot of foam weight, ranging fromabout 3 to 12 inches in height. In addition, the overall diameter of oneor more substrates when lying side by side was about 10 to 18 feet indiameter during successful test runs. One skilled in the art, armed withthis disclosure, will recognize that one or more substrates can be usedin accordance with the present invention. For example, a solid base canbe used and alternatively, two solid halves of a base can be placedadjacent to one another and tied together to form a base with at leastone seam, which allows for the passage of water to prevent corrosion ofthe tank. Further, it can be recognized that the foam density can beincreased to accommodate more than 100 thousand pounds and to providethe load bearing support needed for the present invention.

The next step involves independently encapsulating each substrate with apolyurea elastomer. Once formed to the necessary specifications orsizes, each substrate is individually coated with polyurea forprotection and strength. Preferably, the application is performed usingspecialized equipment that uses high temperatures and high pressures formixing directly in an impingement mix spray gun. In one embodiment, thepolyurea coating is independently applied using a spray device operatingat a temperature of approximately 165 degrees Fahrenheit and a pressureof approximately 1800 pounds per square inch (psi) to encapsulate eachsubstrate. The average coverage of polyurea will be about 50-80 mils,and more preferably about 60 mils coverage. However, one skilled in theart, armed with this disclosure, will recognize that other coverages arealso possible depending on the desired compressive strength of the tankbase and the required application.

The third step in creating the improved tank containment base of thepresent invention involves binding the coated substrates together at thewell site. The substrates are positioned adjacent to one another andbound together with a fastening system. Simultaneously or subsequently,the substrates can be aligned appropriately as discussed above, with themanway entrance aligned with a flat section of the tank base. Whenaligning the base, the plumbing features of the tank is also be takeninto account such that a flat edge is aligned with the manway entranceand plumbing. In test runs, a 45 foot nylon strap with a cam buckle wasused to secure the coated substrates around the outer periphery of theedges and hold the pieces together until the pressure from the weight ofthe tank is applied. Once properly aligned, the AST is placed on thetank base and the fastening system may be removed, if desired, or maystay in place as the discretion of the owner. The polyurea coating ofthe tank base is impervious to the fluid of the AST and will not allowfor the contamination of the substrate or deterioration of the AST. Thecoating also allows for ease of cleaning as the material can now besteamed to extract out any hydrocarbon resins. This also allows for theenvironmentally safe disposal of the base if necessary.

As seen in FIGS. 4 through 9, the independent nature of the substratesforms seams 310 in between the substrates. It is desirable to have asfew seams as possible. FIGS. 5 and 6 illustrate side views of the basesand the corresponding seams possible with the present invention.Straight seams depicted in FIG. 5 allow for any moisture from rainwater,for example, to pass through so as to prevent corrosion of the tank fromstanding water effects. Interlocking seams seen in FIG. 6 also allow formoisture to seep away from the bottom of the tank but also allow foranother embodiment in which to piece or hold together the substrates. Itis noteworthy that the secondary containment system should be as levelas possible with only a slight gradient to allow fluid to “pool” at oneend for removal (i.e. pumping) requirements. Alternatively, FIGS. 7 and8 depict an alternate embodiment wherein the center substrate portion340 is slightly raised above the height of side substrate portions 320and 360. This allows for pooling to occur along either side of the base,rather than in the center of the tank. FIG. 7 further depicts the use offunnels 370 to aid in dispersing fluids away from underneath the tankfor release into specific areas within the secondary containment system.FIG. 8 depicts another embodiment of the present invention, comprising adifferent shape.

While the invention has been particularly described with reference topreferred embodiments, it will be understood by those skilled in the artthat various changes in form and detail may be made therein withoutdeparting from the spirit and scope of the invention. For example, oneskilled in the art, armed with this disclosure, will recognize that avariety of shapes and dimensions are possible with the present inventionand can be tailor made according to the needs of a secondary containmentsystem and/or the weight to be applied to the base. Further, theinvention can be used in and around any area having highly corrosive orhazardous material and with any vessel or storage container. The termsand expressions employed herein have been used as terms of descriptionand not of limitation; and thus, there is no intent of excludingequivalents, but on the contrary it is intended to cover any and allequivalents that may be employed without departing from the spirit andscope of the invention.

What is claimed is:
 1. A tank base sized to provide a load-bearingsupport for an above-ground storage tank and configured to allowmoisture to pass, the above-ground storage tank having a bottom anddefining a diameter, the tank base comprising: a first encapsulatedsubstrate, comprising: a first part comprising polystyrene, the firstpart having a first thickness sized to provide the load-bearing supportfor the above-ground storage tank, the first thickness being at leastabout 3 inches; and a first elastomer encapsulating the first part, thefirst elastomer comprising polyurea, the first elastomer having athickness of at least about 50 mils; wherein the first encapsulatedsubstrate comprises a first planar portion; a second encapsulatedsubstrate positioned adjacent to the first encapsulated substrate, thesecond encapsulated substrate comprising: a second part comprisingpolystyrene, the second part having a second thickness sized to providethe load-bearing support for the above-ground storage tank, the secondthickness being at least about 3 inches; and a second elastomerencapsulating the second part, the second elastomer comprising polyurea,the second elastomer having a thickness of at least about 50 mils;wherein the second encapsulated substrate comprises a second planarportion; wherein the first and second planar portions are coplanar andperpendicular to each of the respective first and second thicknesses ofthe first and second parts; and wherein at least one of the first andsecond encapsulated substrates defines a dimension sized to accommodatethe diameter of the above-ground storage tank and to provide theload-bearing support for the above-ground storage tank, the dimensionextending in a direction that is perpendicular to each of the respectivefirst and second thicknesses of the first and second parts, thedimension ranging from about 10 to 18 feet; and a first seam formedbetween the first and second encapsulated substrates to allow formoisture to pass between the first and second encapsulated substrates sothat moisture is allowed to seep away from the bottom of the tank, viathe first seam, when the tank base provides the load-bearing support forthe above-ground storage tank.
 2. The tank base of claim 1, wherein thetank base has an outer periphery that is generally circular or oblong inshape; wherein each of the first and second encapsulated substratescomprises a curved edge portion; and wherein each of the respectivecurved edge portions of the first and second encapsulated substratesforms part of the outer periphery that is generally circular or oblongin shape.
 3. The tank base of claim 1, wherein the first and secondencapsulated substrates are shaped so that the first seam isinterlocking.
 4. The tank base of claim 1, wherein the tank base has anouter periphery; and wherein the tank base further comprises a strapextending around the outer periphery to hold the first and secondencapsulated substrates together.
 5. The tank base of claim 1, whereinthe first and second encapsulated substrates comprise first and secondedges, respectively; and wherein the second edge interfits with thefirst edge to at least partially form the first seam.
 6. The tank baseof claim 5, wherein the first edge is vertically offset from the secondedge.
 7. A kit which, when assembled, forms a tank base sized to providea load-bearing support for an above-ground storage tank and configuredto allow moisture to pass, the above-ground storage tank defining adiameter, the kit comprising: a first encapsulated substrate,comprising: a first part comprising polystyrene, the first part having afirst thickness sized to provide the load-bearing support for theabove-ground storage tank, the first thickness being at least about 3inches; and a first elastomer encapsulating the first part, the firstelastomer comprising polyurea, the first elastomer having a thickness ofat least about 50 mils; wherein the first encapsulated substratecomprises a first planar portion and a first edge; and a secondencapsulated substrate shaped to be positioned adjacent to the firstencapsulated substrate when the tank base is formed, the secondencapsulated substrate comprising: a second part comprising polystyrene,the second part having a second thickness sized to provide theload-bearing support for the above-ground storage tank, the secondthickness being at least about 3 inches; and a second elastomerencapsulating the second part, the second elastomer comprising polyurea,the second elastomer having a thickness of at least about 50 mils;wherein the second encapsulated substrate comprises a second planarportion and a second edge, the second edge being adapted to interfitwith the first edge to at least partially form a first seam; wherein atleast one of the first and second encapsulated substrates defines adimension sized to accommodate the diameter of the above-ground storagetank and to provide the load-bearing support for the above-groundstorage tank, the dimension extending in a direction that isperpendicular to the first or second thickness of the correspondingfirst or second part, the dimension ranging from about 10 to 18 feet;and wherein, when the tank base is formed and the encapsulated first andsecond substrates are positioned adjacent to one another: the respectivefirst and second planar portions of the encapsulated first and secondsubstrates are coplanar and perpendicular to each of the respectivefirst and second thicknesses of the first and second parts; the firstseam is formed between the encapsulated first and second substrates toallow for moisture to pass between the first and second encapsulatedsubstrates; and the second edge interfits with the first edge to atleast partially form the first seam.
 8. The kit of claim 7, wherein,when the tank base is formed and the encapsulated first and secondsubstrates are positioned adjacent to one another, the tank base has anouter periphery that is generally circular or oblong in shape; whereineach of the first and second encapsulated substrates comprises a curvededge portion; and wherein each of the respective curved edge portions ofthe first and second encapsulated substrates forms part of the outerperiphery that is generally, circular or oblong in shape.
 9. The kit ofclaim 7, wherein the first and second encapsulated substrates are shapedso that, when the tank base is formed and the encapsulated first andsecond substrates are positioned adjacent to one another, the first seamis interlocking.
 10. The kit of claim 7, wherein the first and secondencapsulated substrates are shaped so that, when the tank base is formedand the encapsulated first and second substrates are positioned adjacentto one another, the first edge is vertically offset from the secondedge.
 11. The kit of claim 7, wherein, when the tank base is formed andthe encapsulated first and second substrates are positioned adjacent toone another, the tank base has an outer periphery; and wherein the kitfurther comprises a strap adapted to extend around the outer peripheryof the tank base to hold the first and second encapsulated substratestogether.
 12. A kit which, when assembled, forms a tank base sized toprovide a load-bearing support for an above-ground storage tank andconfigured to allow moisture to pass, the above-ground storage tankdefining a diameter, the kit comprising: a first encapsulated substrate,comprising: a first part comprising polystyrene, the first part having afirst thickness sized to provide the load-bearing support for theabove-ground storage tank, the first thickness being at least about 3inches; and a first elastomer encapsulating the first part, the firstelastomer comprising polyurea, the first elastomer having a thickness ofat least about 50 mils; wherein the first encapsulated substratecomprises a first planar portion; and a second encapsulated substrateshaped to be positioned adjacent to the first encapsulated substratewhen the tank base is formed, the second encapsulated substratecomprising: a second part comprising polystyrene, the second part havinga second thickness sized to provide the load-bearing support for theabove-ground storage tank, the second thickness being at least about 3inches; and a second elastomer encapsulating the second part, the secondelastomer comprising polyurea, the second elastomer having a thicknessof at least about 50 mils; wherein the second encapsulated substratecomprises a second planar portion; wherein at least one of the first andsecond encapsulated substrates defines a dimension sized to accommodatethe diameter of the above-ground storage tank and to provide theload-bearing support for the above-ground storage tank, the dimensionextending in a direction that is perpendicular to the first or secondthickness of the corresponding first or second part, the dimensionranging from about 10 to 18 feet; wherein, when the tank base is formedand the encapsulated first and second substrates are positioned adjacentto one another: the tank base has an outer periphery; the respectivefirst and second planar portions of the encapsulated first and secondsubstrates are coplanar and perpendicular to each of the respectivefirst and second thicknesses of the first and second parts; and thefirst seam is formed between the encapsulated first and secondsubstrates to allow for moisture to pass between the first and secondencapsulated substrates; and wherein the kit further comprises a strapadapted to extend around the outer periphery of the tank base to holdthe first and second encapsulated substrates together.
 13. The kit ofclaim 12, wherein, when the tank base is formed and the encapsulatedfirst and second substrates are positioned adjacent to one another, theouter periphery of the tank base is generally circular or oblong inshape; wherein each of the first and second encapsulated substratescomprises a curved edge portion; and wherein each of the respectivecurved edge portions of the first and second encapsulated substratesforms part of the outer periphery that is generally circular or oblongin shape.
 14. The kit of claim 12, wherein the first and secondencapsulated substrates are shaped so that, when the tank base is formedand the encapsulated first and second substrates are positioned adjacentto one another, the first seam is interlocking.
 15. The kit of claim 12,wherein the first and second encapsulated substrates comprise first andsecond edges, respectively; and wherein the second edge is adapted tointerfit with the first edge to at least partially form the first seam.16. The kit of claim 15, wherein the first and second encapsulatedsubstrates are shaped so that, when the tank base is formed and theencapsulated first and second substrates are positioned adjacent to oneanother, the first edge is vertically offset from the second edge.